Since the operational clock of electronic elements and chips has been increasing rapidly in recent years, the heat resource on a circuit board of a computer is not limited to a central processing unit (CPU); the circuit elements around the CPU, such as capacitors, induction coils and north/south bridge chips, would contribute significantly to the heat generation due to the upgrade of power and processing speed therein. However, the major computer manufacturers have concentrated on the cooling problem of only CPUs, whereas the cooling of the peripheral elements has been largely ignored. Without effectively cooling the peripheral elements, the performance of the CPU will be influenced, and the lifespan of the CPU will even be shortened.
Restricted to the space limit, the conventional cooling mechanism is an electric fan mounted on a heat conductive unit with a plurality of heat radiating fins. The combination is then attached to a heat generating source on a circuit board. The heat in the source is conducted away by the heat conductive unit and then carried away by air flow drive by the fan through the fins. The present invention aims at upgrading the cooling function of a cooling mechanism whereby not only a CPU can get cooled but also the circuit elements around the CPU. The heat radiating device and the flow guiding unit therein disclosed by R.O.C. patent number 527089 comprises a flow guiding tube with a front opening and a rear opening that is smaller than the front opening. The interior portion of the flow guiding tube is provided with a plurality of flow guiding fins. The front opening is connected to the wind exit of a fan, and the rear opening is connected to the heat radiating fins, whereby the air will be driven by the fan and enter the tube from the front opening to the rear opening; the air flow thereby formed will carry heat away from the heat radiating fins within the tube.
However, the cooling mechanism of the prior art can only change the flow rate passing through the tube, and it cannot cool the peripheral circuit elements around the CUP to which the cooling mechanism is attached. Further, the hot air exhausted form the cooling mechanism would diffuses toward the peripheral elements and causes a temperature rise therein. This would shorten the lifespan of the peripheral circuit elements. It is a further disadvantage of the cooling mechanism that there often exists a small gap between the flow guiding tube and the heat radiating unit due to imperfect connection, and therefore the operation of the fan, which is mounted on the tube and of a size substantially larger than the tube, would cause vibration of the tube against the heat radiating unit and produce noises thereon. Moreover, the installation of the flow guiding tube causes an extra production procedure and the associated labor cost. It is a further disadvantage that the conic topology of the flow guide tube of the cooling mechanism would easily cause noises as the air flow hit the converging inner wall of the tube and backward sub-flow of the air that reduces the heat exchange efficiency.
The heat radiating hood disclosed by R.O.C. patent number M240780 comprises a hollow hood body disposed on a computer mother board. The hood body has a top face whereon two opposite sides thereof are connected to at least a sidewall. The lower side of the hood body is open. The combined portion of the top face and the sidewall has one end closed and the other end open and connected to a wind generator. Thereby, the hood body may cover a mother board, confine all of the heat produced by the circuit elements on the mother board and then draw the heat out of the computer by the wind generator.
The latter cooling mechanism of the prior art includes the cooling of all elements it covers. However, this cooling mechanism is complicated to install in a computer and will cause large noises within the hood body. Further, as the number of circuit elements being enclosed increases, the air flow in the hood will experience a larger air drag, therefore reducing the cooling efficiency.